Yeah, ferrar! posted how to do it once.
Search for it in the OS or opensource section.
U can verify the ISOs first using their SHA1 checksums, as suggested in da article.The mediacheck function is highly sensitive, and may report some usable discs as faulty. This result is often caused by disc writing software that does not include padding when creating discs from ISO files. For best results with the mediacheck, boot with the option:
linux ide=nodma